Scheduling for positioning reference signal (prs) in narrowband-internet of things (nb-iot)

ABSTRACT

Wireless communications systems and methods related to communicating positioning reference signals (PRSs) for narrowband communication are provided. A first wireless communication device determines a time-frequency PRS pattern based at least in part on a narrowband communication frequency band configuration and a PRS subframe configuration mode associated with a set of subframes. The first wireless communication device communicates, with a second wireless communication device, a plurality of PRSs using the determined PRS time-frequency pattern in the set of subframes. The PRS subframe configuration mode can indicate a first configuration including a bitmap indicating a set of PRS subframes positioned within a group of contiguous subframes, a second configuration indicating a subset of the group of contiguous subframes that may carry the PRSs, or a combination thereof. The first configuration and/or the second configuration can be used to indicate the set of subframes.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 16/773,546, entitled “SCHEDULING FOR POSITIONINGREFERENCE SIGNAL (PRS) IN NARROWBAND-INTERNET OF THINGS (NB-IOT),” filedJan. 27, 2020, which is a continuation of U.S. Non-Provisional patentapplication Ser. No. 15/718,447, entitled “SCHEDULING FOR POSITIONINGREFERENCE SIGNAL (PRS) IN NARROWBAND-INTERNET OF THINGS (NB-IOT),” filedSep. 28, 2017, which claims priority to and the benefit of the IndianPatent Application No. 201641033621, entitled “SCHEDULING FOR POSITIONREFERENCE SIGNAL (PRS) IN NARROWBAND-INTERNET OF THINGS (NB-IOT),” filedSep. 30, 2016, the U.S. Provisional Patent Application No. 62/423,155,entitled “POSITIONING REFERENCE SIGNAL (PRS) PATTERN FOR DIFFERENTCONFIGURATION SETTINGS,” filed Nov. 16, 2016, and the U.S. ProvisionalPatent Application No. 62/451,966, entitled “POSITIONING REFERENCESIGNAL (PRS) PATTERN FOR DIFFERENT CONFIGURATION SETTINGS,” filed Jan.30, 2017. All of said applications are assigned to the assignee hereofand hereby incorporated by reference in their entirety as if fully setforth below and for all applicable purposes.

TECHNICAL FIELD

The technology discussed in this disclosure relates generally towireless communication systems, and more particularly to signaling andtransmissions of positioning reference signal (PRS) fornarrowband-Internet of Things (NB-IoT). Embodiments enable and providesolutions and techniques allowing wireless communication devices (e.g.,base stations (BSs) and user equipment devices (UEs)) to communicatePRSs for observed-time-difference-of-arrival (OTDOA) based positioningwithout causing collisions with other pre-configured network signals,and thus improving positioning performance.

INTRODUCTION

Wireless communication systems are widely deployed to provide varioustypes of communications such as voice, data, video, etc. These systemsmay be multiple-access systems capable of supporting communication withmultiple access terminals by sharing available system resources (e.g.,bandwidth and transmit power). Examples of such multiple-access systemsinclude code division multiple access (CDMA) systems, time divisionmultiple access (TDMA) systems, frequency division multiple access(FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonalfrequency division multiple access (OFDMA) systems. Typically, awireless communication system comprises several base stations (BSs),wherein each BS communicates with a mobile station or user equipment(UE) using a forward link and each mobile station (or access terminal)communicates with base station(s) using a reverse link.

In recent years, the developments of electronics, information, sensing,and application technologies cause the Internet to evolve from ahuman-oriented network, where a person creates and consumes information,into Internet of Things (IoT), where distributed elements exchange andprocess information. Thus, the demand for serving IoT is increasing. IoTdevices are typically low cost devices with limited processing resourcesand are constrained by power consumption. LTE has been enhanced tosupport narrowband-IoT (NB-IoT) by supporting a reduced bandwidth andreduced transmit power and including power consumption reductiontechniques.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

Embodiments of the present disclosure provide mechanisms forcommunicating PRSs without causing collisions. For example, collisionsthat may possibly occur with other pre-configured or fixed-schedulednetwork signals. A PRS may have a certain time-frequency pattern and mayoccupy certain time-frequency resources, which may overlap withtime-frequency resources pre-configured for a fixed-scheduled networksignal. A BS may indicate a subframe configured for carrying a PRS inseveral formats and may use different PRS time-frequency pattern withdifferent indication formats to avoid the collisions (i.e. efforts forcollision handling or pre-collision avoidance efforts).

For example, in an aspect of the disclosure, a method of wirelesscommunication performed by a user equipment (UE includes receiving aconfiguration including: a first indication including a narrowbandpositioning reference signal (NPRS) bitmap for a group of subframes, theNPRS bitmap including a length corresponding to a number of subframes inthe group of subframes, wherein the NPRS bitmap indicates a firstsubframe of the group of subframes, the first subframe including a firstNPRS; and receiving, based on the first indication, the first NPRS inthe first subframe.

In an additional aspect of the disclosure, a user equipment includes amemory; a transceiver; and a processor communicatively coupled to thememory and the transceiver, wherein the user equipment is configured to:receive a configuration including: a first indication including anarrowband positioning reference signal (NPRS) bitmap for a group ofsubframes, the NPRS bitmap including a length corresponding to a numberof subframes in the group of subframes, wherein the NPRS bitmapindicates a first subframe of the group of subframes, the first subframeincluding a first NPRS; and receive, based on the first indication, thefirst NPRS in the first subframe.

In an additional aspect of the disclosure, a user equipment includesmeans for receiving a configuration including: a first indicationincluding a narrowband positioning reference signal (NPRS) bitmap for agroup of subframes, the NPRS bitmap including a length corresponding toa number of subframes in the group of subframes, wherein the NPRS bitmapindicates a first subframe of the group of subframes, the first subframeincluding a first NPRS; and means for receiving, based on the firstindication, the first NPRS in the first subframe.

In an additional aspect of the disclosure, a non-transitorycomputer-readable medium having program code recorded thereon forexecution by a user equipment is provided. The program code includes:code for causing the user equipment to receive a configurationincluding: a first indication including a narrowband positioningreference signal (NPRS) bitmap for a group of subframes, the NPRS bitmapincluding a length corresponding to a number of subframes in the groupof subframes, wherein the NPRS bitmap indicates a first subframe of thegroup of subframes, the first subframe including a first NPRS; and codefor causing the user equipment to receive, based on the firstindication, the first NPRS in the first subframe.

In an additional aspect of the disclosure, a method of wirelesscommunication includes determining, by a first wireless communicationdevice, a time-frequency positioning reference signal (PRS) patternbased at least in part on a narrowband communication frequency bandconfiguration and a PRS subframe configuration mode associated with aset of subframes; and communicating, by the first wireless communicationdevice with a second wireless communication device, a plurality of PRSsusing the determined PRS time-frequency pattern in the set of subframes.

In an additional aspect of the disclosure, an apparatus includes aprocessor configured to determine a time-frequency positioning referencesignal (PRS) pattern based at least in part on a narrowbandcommunication frequency band configuration and a PRS subframeconfiguration mode associated with a set of subframes; and a transceiverconfigured to communicate, with a second wireless communication device,a plurality of PRSs using the determined PRS time-frequency pattern inthe set of subframes.

In an additional aspect of the disclosure, a computer-readable mediumhaving program code recorded thereon, the program code includes code forcausing a first wireless communication device to determine atime-frequency positioning reference signal (PRS) pattern based at leastin part on a narrowband communication frequency band configuration and aPRS subframe configuration mode associated with a set of subframes; andcode for causing the first wireless communication device to communicate,with a second wireless communication device, a plurality of PRSs usingthe determined PRS time-frequency pattern in the set of subframes.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in conjunction with the accompanying figures. Whilefeatures of the present invention may be discussed relative to certainembodiments and figures below, all embodiments of the present inventioncan include one or more of the advantageous features discussed herein.In other words, while one or more embodiments may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various embodiments of the inventiondiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network according toembodiments of the present disclosure.

FIG. 2 illustrates a narrowband positioning reference signal (NPRS)configuration according to embodiments of the present disclosure.

FIG. 3 is a block diagram of an exemplary user equipment (UE) accordingto embodiments of the present disclosure.

FIG. 4 is a block diagram of an exemplary base station (BS) according toembodiments of the present disclosure.

FIG. 5 illustrates an NPRS transmission method according to embodimentsof the present disclosure.

FIG. 6 illustrates an NPRS transmission method according to embodimentsof the present disclosure.

FIG. 7 illustrates an NPRS scheduling method according to embodiments ofthe present disclosure.

FIG. 8 illustrates an NPRS scheduling method according to embodiments ofthe present disclosure.

FIG. 9 illustrates an NPRS scheduling method according to embodiments ofthe present disclosure.

FIG. 10 illustrates an NPRS scheduling method according to embodimentsof the present disclosure.

FIG. 11 illustrates a valid downlink (DL) subframe indication methodaccording to embodiments of the present disclosure.

FIG. 12 illustrates a valid DL subframe indication method according toembodiments of the present disclosure.

FIG. 13 illustrates an NPRS configuration method according toembodiments of the present disclosure.

FIG. 14 illustrates an NPRS configuration method according toembodiments of the present disclosure.

FIG. 15 illustrates a frequency-division multiple access (FDMA) methodfor NPRS transmissions across multiple cells according to embodiments ofthe present disclosure.

FIG. 16 illustrates a code-division multiple access (CDMA)-based FDMAmethod for NPRS transmission across multiple cells according toembodiments of the present disclosure.

FIG. 17 illustrates an NPRS transmission method including transmitdiversity according to embodiments of the present disclosure.

FIG. 18 is a flow diagram of a method of configuring NPRS transmissionsaccording to embodiments of the present disclosure.

FIG. 19 is a flow diagram of a method of processing NPRSs according toembodiments of the present disclosure.

FIG. 20 is a flow diagram of a method of communicating NPRSs accordingto embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

Techniques described herein may be used for various wirelesscommunication networks such as code-division multiple access (CDMA),time-division multiple access (TDMA), frequency-division multiple access(FDMA), orthogonal frequency-division multiple access (OFDMA),single-carrier FDMA (SC-FDMA) and other networks. The terms “network”and “system” are often used interchangeably. A CDMA network mayimplement a radio technology such as Universal Terrestrial Radio Access(UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and othervariants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. ATDMA network may implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA network may implement a radiotechnology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSMare described in documents from an organization named “3rd GenerationPartnership Project” (3GPP). CDMA2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). The techniques described herein may be used for the wirelessnetworks and radio technologies mentioned above as well as otherwireless networks and radio technologies, such as a next generation(e.g., 5^(th) Generation (5G)) network.

While aspects and embodiments are described in this application byillustration to some examples, those skilled in the art will understandthat additional implementations and use cases may come about in manydifferent arrangements and scenarios. Innovations described herein maybe implemented across many differing platform types, devices, systems,shapes, sizes, packaging arrangements. For example, embodiments and/oruses may come about via integrated chip embodiments and othernon-module-component based devices (e.g., end-user devices, vehicles,communication devices, computing devices, industrial equipment,retail/purchasing devices, medical devices, AI-enabled devices, etc.).While some examples may or may not be specifically directed to use casesor applications, a wide assortment of applicability of describedinnovations may occur. Implementations may range a spectrum fromchip-level or modular components to non-modular, non-chip-levelimplementations and further to aggregate, distributed, or OEM devices orsystems incorporating one or more aspects of the described innovations.In some practical settings, devices incorporating described aspects andfeatures may also necessarily include additional components and featuresfor implementation and practice of claimed and described embodiments. Itis intended that innovations described herein may be practiced in a widevariety of devices, chip-level components, systems, distributedarrangements, end-user devices, etc.

In LTE, BSs and UEs may exchange several reference signals forestimating channel states, link quality, and the locations of the UEs.For example, BSs may transmit PRSs and a UE may compute various timingmeasurements based on the PRSs received from multiple neighboring BSs.The BSs may determine the UE location based on the UE's timingmeasurements. NB-IoT may employ similar mechanisms for UE-locationestimation. However, the scheduling of PRSs in NB-IoT may be challengingdue to the co-existence of NB-IoT signals and other LTE signals.

The present disclosure describes NPRS scheduling and transmissionmechanisms and techniques that may avoid collisions with other LTEsignals and improve NPRS performances. In the disclosed embodiments, aBS may configure a plurality of positioning subframes in a plurality ofDL subframes for carrying NPRSs, where at least one positioning subframemay overlap with a DL subframe pre-configured for carrying afixed-scheduled or pre-determined signal (e.g., a reference signal).When an NPRS and a reference signal are mapped to the sametime-frequency resource (e.g., a frequency tone within a time symbol),the BS may transmit the reference signal or the NPRS at thetime-frequency resource depending on how the BS indicates thepositioning subframes within the DL subframes.

In an embodiment, a BS may mark subframes carrying NPRSs as invalidsubframe for carrying DL data and determine an NPRS time-frequencypattern irrespective of time-frequency resources pre-configured for afixed-scheduled channel signal.

In an embodiment, a BS may indicate that a subframe carries an NPRS, butdoes not mark the subframe as an invalid DL data subframe. In such anembodiment, the BS may determine an NPRS time-frequency pattern byexcluding time-frequency resources pre-configured for a fixed-scheduledchannel signal and skip over the pre-configured time-frequency resourcesduring NPRS transmissions. In other words, the BS may puncture thetime-frequency pattern of the NPRS to exclude the pre-configuredtime-frequency resource.

In an embodiment, a BS may transmit an NPRS with repetitions (e.g.,about 4) in contiguous subframes and may reduce the number ofrepetitions or skip over subframes that are pre-configured forfixed-scheduled channel signals. The disclosed embodiments are suitablefor use in NPRS communications within an in-band communication frequencyband, a guard band, a standalone frequency band, and/or a non-anchoringsubcarrier of a carrier aggregation. While the disclosed embodiments aredescribed in the context of NPRSs. The disclosed embodiments may beapplied to signaling and/or scheduling of other fixed-scheduled channelsignals in a wireless network. The NPRSs may also be referred to as PRSsin the disclosed embodiments.

FIG. 1 illustrates a wireless communication network 100 according toembodiments of the present disclosure. The network 100 may include anumber of UEs 102, as well as a number of BSs 104. The BSs 104 mayinclude an Evolve Node B (eNodeB). A BS 104 may be a station thatcommunicates with the UEs 102 and may also be referred to as a basetransceiver station, a node B, an access point, and the like.

The BSs 104 communicate with the UEs 102 as indicated by communicationsignals 106. A UE 102 may communicate with the BS 104 via an uplink (UL)and a downlink (DL). The downlink (or forward link) refers to thecommunication link from the BS 104 to the UE 102. The UL (or reverselink) refers to the communication link from the UE 102 to the BS 104.The BSs 104 may also communicate with one another, directly orindirectly, over wired and/or wireless connections, as indicated bycommunication signals 108.

The UEs 102 may be dispersed throughout the network 100, as shown, andeach UE 102 may be stationary or mobile. The UE 102 may also be referredto as a terminal, a mobile station, a subscriber unit, etc. The UE 102may be a cellular phone, a smartphone, a personal digital assistant, awireless modem, a laptop computer, a tablet computer, an IoT device,vehicle, medical device, industrial equipment, wearable, sportsequipment, implantable device, etc. The network 100 is one example of anetwork to which various aspects of the disclosure apply.

Each BS 104 may provide communication coverage for a particulargeographic area. In 3GPP, the term “cell” can refer to this particulargeographic coverage area of a BS and/or a BS subsystem serving thecoverage area, depending on the context in which the term is used. Inthis regard, a BS 104 may provide communication coverage for a macrocell, a pico cell, a femto cell, and/or other types of cell. A macrocell generally covers a relatively large geographic area (e.g., severalkilometers in radius) and may allow unrestricted access by UEs withservice subscriptions with the network provider. A pico cell maygenerally cover a relatively smaller geographic area and may allowunrestricted access by UEs with service subscriptions with the networkprovider. A femto cell may also generally cover a relatively smallgeographic area (e.g., a home) and, in addition to unrestricted access,may also provide restricted access by UEs having an association with thefemto cell (e.g., UEs in a closed subscriber group (CSG), UEs for usersin the home, and the like). A BS for a macro cell may be referred to asa macro BS. A BS for a pico cell may be referred to as a pico BS. A BSfor a femto cell may be referred to as a femto BS or a home BS.

In the example shown in FIG. 1, the BSs 104 a, 104 b and 104 c areexamples of macro BSs for the coverage areas 110 a, 110 b and 110 c,respectively. The BSs 104 d and 104 e are examples of pico and/or femtoBSs for the coverage areas 110 d and 110 e, respectively. As will berecognized, a BS 104 may support one or multiple (e.g., two, three,four, and the like) cells.

The network 100 may also include relay stations. A relay station is astation that receives a transmission of data and/or other informationfrom an upstream station (e.g., a BS, a UE, or the like) and sends atransmission of the data and/or other information to a downstreamstation (e.g., another UE, another BS, or the like). A relay station mayalso be a UE that relays transmissions for other UEs. A relay stationmay also be referred to as a relay BS, a relay UE, a relay, and thelike.

The network 100 may support synchronous or asynchronous operation. Forsynchronous operation, the BSs 104 may have similar frame timing, andtransmissions from different BSs 104 may be approximately aligned intime. For asynchronous operation, the BSs 104 may have different frametiming, and transmissions from different BSs 104 may not be aligned intime.

In some implementations, the network 100 utilizes orthogonal frequencydivision multiplexing (OFDM) on the downlink and single-carrierfrequency division multiplexing (SC-FDM) on the UL. OFDM and SC-FDMpartition the system bandwidth into multiple (K) orthogonal subcarriers,which are also commonly referred to as tones, bins, or the like. Eachsubcarrier may be modulated with data. In general, modulation symbolsare sent in the frequency domain with OFDM and in the time domain withSC-FDM. The spacing between adjacent subcarriers may be fixed, and thetotal number of subcarriers (K) may be dependent on the systembandwidth. For example, K may be equal to 72, 180, 300, 600, 900, and1200 for a corresponding system bandwidth of 1.4, 3, 5, 10, 15, or 20megahertz (MHz), respectively. The system bandwidth may also bepartitioned into sub-bands. For example, a sub-band may cover 1.08 MHz,and there may be 1, 2, 4, 8 or 16 sub-bands for a corresponding systembandwidth of 1.4, 3, 5, 10, 15, or 20 MHz, respectively. In anembodiment, the network 100 can support NB-IoT or MTC over LTE, forexample, in LTE Release 13, where a portion of a system bandwidth may bereused. For example, the network 100 may operate at a system bandwidthof about 20 MHz and support NB-IoT or MTC, where each UE 102 may beallocated with a reduced bandwidth of about 180 kilohertz (kHz) forNB-IoT and about 1.4 MHz to about 5 MHz for MTC.

In an embodiment, the network 100 can be a LTE network. In such anembodiment, the BSs 104 can assign or schedule transmission resources(e.g., in the form of time-frequency resource blocks) for DL and ULtransmissions in the network 100. The communication can be in the formof radio frames. A radio frame may be divided into a plurality ofsubframes. In a FDD mode, simultaneous UL and DL transmissions may occurin different frequency bands. In a TDD mode, UL and DL transmissionsoccur at different time periods using the same frequency band. Forexample, a subset of the subframes in a radio frame may be used for DLtransmissions and another subset of the subframes may be used for ULtransmissions. The DL and UL subframes can be shared among the BSs 104and the UEs 102, respectively.

The DL subframes and the UL subframes can be further divided intoseveral regions. For example, each DL or UL subframe may havepre-defined regions for transmissions of reference signals, controlinformation, and data. Reference signals are pre-determined signals thatfacilitate the communications between the BSs 104 and the UEs 102. Forexample, a reference signal can have a particular pilot pattern orstructure, where pilot tones may span across an operational bandwidth orfrequency band, each positioned at a pre-defined time and a pre-definedfrequency. Control information may include resource assignments andprotocol controls. Data may include protocol data and/or operationaldata.

To support the operation of the network 100, the BSs 104 may broadcastseveral signals periodically at a fixed schedule, for example, withpre-determined locations within a subframe. Some examples offixed-scheduled signals may include a physical broadcast channel (PBCH)signal, a primary synchronization signal (PSS), and a secondarysynchronization signal (SSS). The PBCH signal may carry systeminformation, such as cell bandwidths and frame configurations, cellaccess information, and neighbor cell information. The PSS and SSSinclude pre-determine signal sequences to allow a UE 102 to synchronizewith a BS 104 for communication. To support NB-IoT, the BSs 104 maybroadcast similar signals, such as a narrowband PBCH (NPBCH) signal, anarrowband PSS (NPSS), a narrowband SSS (NSSS) corresponding to thePBCH, the PSS, and the SSS, respectively. In addition, the BSs 104 maybroadcast a system information block-narrowband (SIB-NB) signal toindicate NB-IoT specific system information.

The network 100 may support UE-location estimation. For example, the BSs104 may transmit LTE positioning reference signals (PRSs) to the UEs102. A UE 102 may measure time of arrivals (TOAs) of the LTE PRSsreceived from multiple BSs 104 and report the timing measurements to aBS 104 serving the UE 102. The serving BS 104 may determine the locationof the UE 102 based on the TOAs obtained from the UE 102. In someembodiments, the serving BS 104 may mute a LTE PRS transmission (e.g.,transmit with zero power) at a particular time to allow the UE 102 toreceive LTE PRSs from neighboring BSs 104 with weaker signal strengths.The network 100 can support UE-location estimation for NB-IoT byemploying similar mechanisms. For example, the BSs 104 may transmit thesame LTE PRS to the UEs 102. However, the use of LTE PRS may not performwell at a low signal-to-noise ratio (SNR). An alternative approach maybe to use N-SSS for UE-location estimation instead of the LTE PRS.However, the use of N-S SS may not benefit from muting.

FIG. 2 illustrates an NPRS configuration 200 according to embodiments ofthe present disclosure. The configuration 200 is employed by the BSs 104to facilitate UE-location estimation. In FIG. 2, the x-axis representstime in some constant units and the y-axis represents frequency in someconstant units. The configuration 200 shows two consecutive subframes210. Each subframe 210 includes a plurality of symbols 212 and eachsymbol 212 includes a plurality of frequency tones 218. The first 3symbols 212, which is referred to as a control region 214, are used fortransmission of control information, such as allocations andtransmission parameters. The remaining symbols 212 in the subframe 210are referred to as a data region 216. In the LTE context, the controlregion 214 is referred to as physical downlink control channel (PDCCH)and the data region 216 is referred to as a physical downlink sharedchannel (PDSCH). A plurality of cell-specific reference signal (CRS) maybe transmitted in the subframe 210 in a plurality of frequency tones218, shown as CRS 230. As shown, the CRS 230 are distributed within thecontrol region 214 and the data region 216.

In the configuration 200, a N-PRS signal may be transmitted based on 2frequency tones 218, shown as NPRS 220, repeated over the subframe 210in the data region 216. As shown, the frequency tones 218 of the NPRS220 are configured to be non-overlapping with the frequency tones of theCRS 230. In addition, the frequency tones 218 of the NPRS 220 areconfigured in a staggered pattern across the two consecutive subframes210, where the frequency tones 218 of the NPRS 220 are offset by 1between adjacent subframes 210. The repetitions in the NPRS 220 allowthe NPRS 220 to operate at a low SNR and the staggering allows for alarger dynamic range of TOA estimation.

FIG. 3 is a block diagram of an exemplary UE 300 according toembodiments of the present disclosure. The UE 300 may be a UE 102 asdiscussed above. As shown, the UE 300 may include a processor 302, amemory 304, an NPRS processing module 308, a transceiver 310 including amodem subsystem 312 and a RF unit 314, and an antenna 316. Theseelements may be in direct or indirect communication with each other, forexample via one or more buses.

The processor 302 may include a central processing unit (CPU), a digitalsignal processor (DSP), an application-specific integrated circuit(ASIC), a controller, a field programmable gate array (FPGA) device,another hardware device, a firmware device, or any combination thereofconfigured to perform the operations described herein. The processor 302may also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The memory 304 may include a cache memory (e.g., a cache memory of theprocessor 302), random access memory (RAM), magnetoresistive RAM (MRAM),read-only memory (ROM), programmable read-only memory (PROM), erasableprogrammable read only memory (EPROM), electrically erasableprogrammable read only memory (EEPROM), flash memory, solid state memorydevice, hard disk drives, other forms of volatile and non-volatilememory, or a combination of different types of memory. In an embodiment,the memory 304 includes a non-transitory computer-readable medium. Thememory 304 may store instructions 306. The instructions 306 may includeinstructions that, when executed by the processor 302, cause theprocessor 302 to perform the operations described herein with referenceto the UEs 102 in connection with embodiments of the present disclosure.Instructions 306 may also be referred to as code. The terms“instructions” and “code” should be interpreted broadly to include anytype of computer-readable statement(s). For example, the terms“instructions” and “code” may refer to one or more programs, routines,sub-routines, functions, procedures, etc. “Instructions” and “code” mayinclude a single computer-readable statement or many computer-readablestatements.

The NPRS processing module 308 may be implemented via hardware,software, or combinations thereof. For example, the NPRS processingmodule 308 may be implemented as a processor, circuit, and/orinstructions 406 stored in the memory 304 and executed by the processor302. The NPRS processing module 308 may be used for various aspects ofthe present disclosure. For example, the NPRS processing module 308 isconfigured to perform timing measurements based on NPRSs such as theNPRS 220 received from BSs such as the BSs 104, as described in greaterdetail herein.

As shown, the transceiver 310 may include the modem subsystem 312 andthe RF unit 314. The transceiver 310 can be configured to communicatebi-directionally with other devices, such as the BSs 104. The modemsubsystem 312 may be configured to modulate and/or encode the data fromthe memory 304 and/or the NPRS processing module 308 according to amodulation and coding method (MCS), e.g., a low-density parity check(LDPC) coding method, a turbo coding method, a convolutional codingmethod, a digital beamforming method, etc. The RF unit 314 may beconfigured to process (e.g., perform analog to digital conversion ordigital to analog conversion, etc.) modulated/encoded data from themodem subsystem 312 (on outbound transmissions) or of transmissionsoriginating from another source such as a UE 102 or a BS 104. Althoughshown as integrated together in transceiver 310, the modem subsystem 312and the RF unit 314 may be separate devices that are coupled together atthe UE 102 to enable the UE 102 to communicate with other devices.

The RF unit 314 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information), to the antenna 316 fortransmission to one or more other devices. The antenna 316 may furtherreceive data messages transmitted from other devices. This may include,for example, reception NPRSs according to embodiments of the presentdisclosure. The antenna 316 may provide the received data messages forprocessing and/or demodulation at the transceiver 310. Although FIG. 3illustrates antenna 316 as a single antenna, antenna 316 may includemultiple antennas of similar or different designs in order to sustainmultiple transmission links. The RF unit 314 may configure the antenna316

FIG. 4 is a block diagram of an exemplary BS 400 according toembodiments of the present disclosure. The BS 400 may be a BS 104 asdiscussed above. As shown, the BS 400 may include a processor 402, amemory 404, an NPRS configuration module 408, a transceiver 410including a modem subsystem 412 and a RF unit 414, and an antenna 416.These elements may be in direct or indirect communication with eachother, for example via one or more buses.

The processor 402 may have various features as a specific-typeprocessor. For example, these may include a CPU, a DSP, an ASIC, acontroller, a FPGA device, another hardware device, a firmware device,or any combination thereof configured to perform the operationsdescribed herein. The processor 402 may also be implemented as acombination of computing devices, e.g., a combination of a DSP and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The memory 404 may include a cache memory (e.g., a cache memory of theprocessor 402), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, asolid state memory device, one or more hard disk drives, memristor-basedarrays, other forms of volatile and non-volatile memory, or acombination of different types of memory. In some embodiments, thememory 404 may include a non-transitory computer-readable medium. Thememory 404 may store instructions 406. The instructions 406 may includeinstructions that, when executed by the processor 402, cause theprocessor 402 to perform operations described herein. Instructions 406may also be referred to as code, which may be interpreted broadly toinclude any type of computer-readable statement(s) as discussed abovewith respect to FIG. 3.

The NPRS configuration module 408 may be implemented via hardware,software, or combinations thereof. For example, the NPRS configurationmodule 408 may be implemented as a processor, circuit, and/orinstructions 406 stored in the memory 404 and executed by the processor402. The NPRS configuration module 408 may be used for various aspectsof the present disclosure. For example, the NPRS configuration module408 may schedule NPRS transmission, configure NPRS frequency patterns,and signal NPRS configurations, as described in greater detail herein.

As shown, the transceiver 410 may include the modem subsystem 412 andthe RF unit 414. The transceiver 410 can be configured to communicatebi-directionally with other devices, such as the UEs 102 and/or anothercore network element. The modem subsystem 412 may be configured tomodulate and/or encode data according to a MCS, e.g., a LDPC codingmethod, a turbo coding method, a convolutional coding method, a digitalbeamforming method, etc. The RF unit 414 may be configured to process(e.g., perform analog to digital conversion or digital to analogconversion, etc.) modulated/encoded data from the modem subsystem 412(on outbound transmissions) or of transmissions originating from anothersource such as a UE 102. Although shown as integrated together intransceiver 410, the modem subsystem 412 and the RF unit 414 may beseparate devices that are coupled together at the BS 104 to enable theBS 104 to communicate with other devices.

The RF unit 414 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information), to the antenna 416 fortransmission to one or more other devices. This may include, forexample, transmission of information to complete attachment to a networkand communication with a camped UE 102 according to embodiments of thepresent disclosure. The antenna 416 may further receive data messagestransmitted from other devices and provide the received data messagesfor processing and/or demodulation at the transceiver 410. Although FIG.4 illustrates antenna 416 as a single antenna, antenna 416 may includemultiple antennas of similar or different designs in order to sustainmultiple transmission links.

FIG. 5 illustrates an NPRS transmission method 500 according toembodiments of the present disclosure. The method 500 is employed by theBSs 104 and 400 to transmit the NPRS 220 in the network 100. In FIG. 5,the x-axis represents frequency in some constant units and the y-axisrepresents power in some constant units. A BS 104 may transmit NPRSs atvarious frequencies when operating over a LTE network. In oneembodiment, a BS 104 may transmit an NPRS 532 (e.g., the NPRS 220)within a LTE signal band 514 of a LTE system band 510, which may bereferred to as an inband mode. In such embodiment, the scheduling of theNPRS 532 (e.g., the NPRS 220) is required to account for scheduling ofother LTE signals and NB-IoT signals in order to avoid collisions, asdescribed in greater detail herein. In another embodiment, a BS 104 maytransmit an NPRS 531 (e.g., the NPRS 220) within a LTE guard band 512 ofthe LTE system band 510, which may be referred to as a guard band mode.In another embodiment, a BS 104 may transmit an NPRS 533 in a frequencyband 520 outside the LTE system band 510, which may be referred to as astandalone mode. The scheduling of the NPRS 532 or 533 may be lessrestricted since the NPRS 532 or 533 are transmitted outside of the LTEsignal band 514.

FIG. 6 illustrates an NPRS transmission method 600 according toembodiments of the present disclosure. The method 600 is employed by theBSs 104 and 400 to transmit the NPRS 220 in the network 100 when thenetwork 100 employs carrier aggregation. In FIG. 6, the x-axisrepresents frequency in some constant units and the y-axis representspower in some constant units. FIG. 6 illustrates carrier aggregationwith two signal carriers 610 and 620 for purposes of simplicity ofdiscussion, though it will be recognized that embodiments of the presentdisclosure may scale to many more signal carriers. For example, thesignal carrier 610 may be an anchor carrier and the signal carrier 620may be a non-anchor carrier. The anchor signal carrier 610 may carryfixed-scheduled channel signals such as PBCH, PSS, SSS, NPCH, NPSS, andNSSS. Thus, a BS 104 may transmit an NPRS 631 (e.g., the NPRS 220) inthe non-anchor signal carrier 620 to avoid collisions with thefixed-scheduled channel signals.

FIGS. 7 and 8 illustrate NPRS scheduling mechanisms for avoidingcollisions with fixed-scheduled channel signals when transmitting NPRSssuch as the NPRSs 220 and 532 within a LTE signal band such as the LTEsignal band 514. FIG. 7 illustrates an NPRS scheduling method 700according to embodiments of the present disclosure. The method 700 canbe employed by the BSs 104 and 400. The method 700 shows two radioframes 710. For example, each radio frame 710 has a duration of about 10milliseconds (ms). Each radio frame 710 includes ten subframes 712. Forexample, each subframe 712 has a duration of about 1 ms. The subframes712 are indexed from 0 to 9.

For example, a BS 104 may schedule transmissions in a DL direction or aUL direction in the subframes 712. The BS 104 may schedule severalsignals periodically in a fixed schedule. The fixed-scheduled channelsignals may include a NPBCH signal 722, a SIB-NB signal 724, a NPSS 726,and a NSSS 728. For example, the NPBCH signal 722 is scheduled fortransmission in a subframe 712 indexed 0, denoted as SFO, with aperiodicity of one radio frame 710. The SIB-NB signal 724 is scheduledfor transmission in a subframe 712 indexed 4, denoted as SF4, with aperiodicity of one or more radio frame 710. The NPSS 726 is scheduledfor transmission in a subframe 712 indexed 5, denoted as SF5, with aperiodicity of one radio frame 710. The NSSS 728 is scheduled fortransmission in a subframe 712 indexed 9, denoted as SF9, with aperiodicity of two radio frames 710. As shown, the NSSS 728 is scheduledin the radio frame 710 a and is skipped in the radio frame 710 b. Forexample, the NSSS 728 may be scheduled in even or odd indexed radioframes 710.

As described above, a BS may transmit an NPRS with repetitions to gainperformance for low SNR conditions. As an example, a network may beconfigured to employ an NPRS with 4 repetitions. The repetitions may betransmitted across contiguous subframes 712 to achieve the bestperformance for signal combining since channel taps may change when therepetitions are separated by one or more subframes. As shown, the radioframe 710 a has two groups of consecutive subframes 712 (e.g., indexed 1to 3 and indexed 6 to 8) without fixed-scheduled channel signals. In themethod 700, the BS may reduce the number of repetitions to avoidcollisions (e.g., marked by symbols x) with the fixed-scheduled channelsignals. As shown, the BS configures the three available consecutivesubframes 712 indexed 1 to 3 as positioning subframes for transmittingthree NPRS 730 (e.g., the NPRSs 220 and 532) repetitions and drop thefourth repetition for transmission. The subframes 712 indexed 1 to 3configured for the NPRS 730 transmissions are referred to as positioningsubframes. A UE (e.g., the UEs 102 and 300) may monitor for aconfiguration from the BS indicating the positioning subframes andreceive the NPRSs 730 according to the configuration.

FIG. 8 illustrates an NPRS scheduling method 800 according toembodiments of the present disclosure. The method 800 can be employed bythe BSs 104 and 400 to transmit NPRSs with four repetitions. In themethod 800, a BS may skip over fixed-scheduled channel signals andcomplete the four repetitions instead of reducing the number ofrepetitions as in the method 700. The method 800 is illustrated usingthe same radio frame configuration as in the method 700. As shown, theBS configures the three available consecutive subframes 712 indexed 1 to3 and a following available subframe 712 indexed 6 as positioningsubframes for transmitting four NPRS 730 repetitions. Similar to themethod 700, a UE (e.g., the UEs 102 and 300) may monitor for aconfiguration from the BS indicating the positioning subframes andreceive the NPRSs 730 according to the configuration.

Although the method 700 and 800 are illustrated with transmission of theNPRSs 730 with four repetitions in the radio frame 710 a, the NPRSs 730may be transmitted with any suitable number of repetitions and/or in theradio frame 710 b instead. In addition, the NPRS 730 may be transmittedin different groups of consecutive subframes 712 may have differentfrequency patterns (e.g., different frequency tones 218 or subcarriers).When the BS configures positioning subframes in the radio frame 710 b,the BS may include the subframe 712 indexed 9 where the NSSS 728 is notscheduled. However, UEs (e.g., the UEs 102 and 300) in the network arerequired to be synchronized in radio frame numbers with BSs.

FIGS. 9 and 10 illustrate NPRS scheduling mechanisms for avoidingcollisions with reference signals (RSs) when transmitting NPRSs such asthe NPRSs 220 and 532 within a LTE signal band such as the LTE signalband 514. Some examples of reference signals may include LTE CRSs (e.g.,the CRS 230) and narrowband reference signals (NRSs). NRSs may providesimilar functionalities as the LTE CRSs. In FIGS. 9 and 10, the x-axisrepresents time in some constant units and the y-axis representsfrequency in some constant units.

FIG. 9 illustrates an NPRS scheduling method 900 according toembodiments of the present disclosure. The method 900 can be employed bythe BSs 104 and 400. For example, a subframe 910 (e.g., the subframes210 and 712) may be configured to carry a RS 950. The RS 950 may bemapped to a plurality of frequency tones 930 (e.g., the frequency tones218) in a control region 914 (e.g., the control region 214) and a dataregion 916 (e.g., the data region 216) of the subframe 910. As anexample, a BS may configure the subframe 910 as a positioning subframefor transmitting an NPRS 940 (e.g., the NPRSs 220, 532, and 730). In themethod 900, the BS may drop the RS 950 at the symbols where thefrequency tones 930 overlap with the NPRS 940 and transmit the NPRS 940at the overlapped frequency tones 930. The overlapped frequency tones930 are shown as dashed boxes. In some embodiments, the BS may drop theRS 950 at the symbols that carry the NPRS 940 irrespective of whetherthere is an overlapped frequency tone 930 between the NPRS 940 and theRS 950. If a receiving UE (e.g., a LTE Release 13 UE) is not aware ofthe configuration of the NPRS 940, the UE performance may be degraded.Thus, the BS may avoid scheduling NPRSs in subframes that carry DL datafor the UE.

FIG. 10 illustrates an NPRS scheduling method 1000 according toembodiments of the present disclosure. The method 1000 can be employedby the BSs 104 and 400. The method 1000 is illustrated with the samesubframe configuration as the method 900. However, in the method 1000,the BS may skip over the frequency tones 930 for transmission of theNPRS 940 in the symbols that are configured for the RS 950. As shown,the NPRS 940 and the RS 950 are interleaved in the same frequency band.Thus, the NPRS-density may be lower in the method 1000 when compared tothe method 900.

As described above, the LTE Release 13 includes support for NB-IoT, forexample, within a LTE signal band such as the LTE signal band 514. A BS(e.g., the BS 104) may schedule a plurality of DL subframes (e.g., thesubframes 210, 712, 910) for transmitting DL data to NB-IoT devices(e.g., the UEs 102). For example, the BS (e.g., the BS 104) may indicatewhether a DL subframe carries a DL allocation by using a valid DLsubframe mask (e.g., a bit mask). As an example, a bit value of 1 mayindicate a DL subframe is scheduled with DL data transmission and a bitvalue of 0 may indicate a DL subframe is not scheduled for DL datatransmission. Thus, a UE may decode the DL subframes that are indicatedas valid DL subframes and skip decoding the DL subframes that areindicated as invalid DL subframes. FIGS. 11 and 12 illustrate valid DLsubframe indication mechanisms.

FIG. 11 illustrates a valid DL subframe indication method 1100 accordingto embodiments of the present disclosure. The method 1100 may beemployed by the BSs 104 and 400. FIG. 11 illustrates a plurality ofradio frames 1110, indexed from n to (n+3), similar to the radio frames710. As shown, the radio frame 1110 c indexed (n+2) is configured with aplurality of positioning subframes 1122 for transmitting NPRSs 1130(e.g., the NPRSs 220, 532, 730, and 940). In the method 1100, a BS mayindicate the subframes 1120 in the radio frame 1110 c as invalid DLsubframes. As shown, a bitmask 1140 indicates bit values of ones for allsubframes in the radio frames 1110 a, 1110 b, and 1110 d that are notconfigured with positioning subframes and indicates bit values of zeroesfor all subframes 1120 in the radio frame 1110 c as invalid DLsubframes. The method 1100 is suitable for use when the BS operates withUEs (e.g., the UEs 102 and 300) that are not aware of the configurationand scheduling of the NPRSs 1130. For example, the UEs may be LTERelease 13 UEs.

FIG. 12 illustrates a valid DL subframe indication method 1200 accordingto embodiments of the present disclosure. The method 1200 may beemployed by the BSs 104 and 400. The method 1200 is illustrated with thesame radio frame configuration as the method 1200. However, in themethod 1200, the BS may indicate that all subframes in the radio frames1110 are valid including the radio frame 1110 c configured with thepositioning subframes 1122. The method 1200 is suitable for use when theBS operates with UEs (e.g., the UEs 102 and 300) that are aware of theconfiguration and scheduling of the NPRSs 1130, which may include thelocations of the positioning subframes 1122 and repetitions of the NPRSs1130. For example, the UEs may skip over the positioning subframes 1122during DL data decoding.

As described above, a BS may employ any of the methods 700-1200 forscheduling NPRS transmissions to avoid collisions with high prioritychannels or signals when operating in a LTE signal frequency band (e.g.,the LTE signal frequency band 514). In one embodiment, a BS may employthe method 700 or 800 to avoid collisions with fixed-scheduled channelsignals. In addition, a BS may employ the method 700 or 800 inconjunction with the method 1100 or 1200. For example, the BS may reducethe number of NPRS repetitions or skip the valid DL subframes andcontinue to complete all the repetitions when subframes are separated bythe DL subframes.

In another embodiment, the BS may employ the method 900 or 1000 when apositioning subframe includes NRS signals. However, if a receiving UE isnot aware of the NPRS configuration, the UE performance may be degraded.Thus, the BS may avoid scheduling NPRSs in subframes with DLallocations. The BS may employ the method 1000 when a positioningsubframe includes LTE CRS, CSI-RS, or PRS. In another embodiment, the BSmay reuse the LTE PRS instead of transmitting an NPRS when the LTE PRSand the NPRS have the same frequency pattern.

In some embodiments, the BS may employ different frequency patterns forNPRS in in-band LTE and standalone deployments. For example, when NB-IOTis deployed in-band of an existing LTE deployment, NPRS may be scheduledon a non-anchor carrier avoiding collisions with N-RS and other NB-IOTcontrol channels (e.g., NPBCH, NPSS, NSSS). However, N-PRS on non-anchorcarrier would need to be punctured to avoid collision with LTE controlsignaling (e.g., PDCCH and CRS symbols). When NB-IOT is a standalonedeployment, non-anchor carrier may not be available but there is no needto co-exist with LTE signaling (CRS, CSI-RS, PDCCH, and other LTEspecific signaling), so N-PRS may be scheduled on the anchor carriersuch that it does not overlap with any narrowband broadcast channels,and N-PRS punctured on NRS symbols.

In some embodiments, the BS may employ different frequency patterns forNPRSs. For example, the BS may employ different NPRS frequency patternsin valid DL subframes and in invalid DL subframes. The BS may employdifferent NPRS frequency patterns across different groups of consecutivesubframes. The BS may drop or skip NPRS transmissions in groups ofconsecutive subframes.

FIG. 13 illustrates an NPRS configuration method 1300 according toembodiments of the present disclosure. The method 1300 may be employedby the BSs 104 and 400 and the UEs 102 and 300. In FIG. 13, the x-axisrepresents time in some constant units and the y-axis representsfrequency in some constant units. In the method 1300, a BS may configurea plurality of positioning subframes 1310 in a plurality of subframes910 within a radio frame 1110. For example, the subframes 910 indexed 1to 3 are configured as positioning subframes 1310. The BS may mark thepositioning subframes 1310 as invalid DL data subframes. The invalid DLdata subframes may not carry any DL data. As such, UEs may not processreferences signals (e.g., pre-configured) for demodulation or decodedata from the invalid DL data subframes. For example, the BS may employa bitmask 1302 to indicate the NPRS subframe configuration. As shown,the bitmask 1302 indicates bit values of zeros for subframes 910 thatare not configured with NPRSs and indicates bit values of ones forsubframes 910 as invalid DL subframes. The bitmask 1302 may have a fixedbit-length and may be of any suitable bit-length. In some embodiments,the bitmask 1302 may have a bit-length corresponding to a periodicity ofa fixed-scheduled channel signal.

A positioning subframe 1310 or a subframe 910 may include a number oftime-frequency resource blocks 1360 spanning a number of symbols 212(e.g., about 14 and indexed from 0 to 13) in time and a number offrequency tones 930 (e.g., about 12) in frequency. The NPRS 1340 ismapped to a number of time-frequency resources 1350 shown aspattern-filled boxes. Each time-frequency resource 1350 corresponds to afrequency tone 930 in a symbol 212.

As an example, at least one of the subframes 910 indexed 1, 2, or 3 maybe pre-configured to carry a fixed scheduled channel signals (e.g.,NBCH, SIB-NB, NPSS, NSSS, NRS, CRS, CSI-RS, or PRS). Since the BS marksthe positioning subframes 1310 as invalid DL data subframes, the BS maydetermine a time-frequency pattern or time-frequency resources 1350 forthe NPRSs 1340 without considering a time-frequency pattern ortime-frequency resources (e.g., the time-frequency resources 1370) thatare pre-configured for the fixed scheduled channel signal. As shown, theNPRS 1340 occupies the pre-configured time-frequency resources 1370.

In an embodiment, the time-frequency pattern for the NPRSs 1340 may bepre-determined and known to BSs and UEs. For example, a BS may transmita bitmask 1302 (e.g., a configuration) to indicate the positioningsubframes 1310 in the subframes 910 and transmits the NPRSs 1340 in thepre-determined time-frequency pattern. A UE may receive the bitmask 1302and monitor for an NPRS 1340 in the positioning subframes 1310 indicatedby the bitmask 1302. The UE may receive the NPRSs 1340 based on thepre-determined NPRS time-frequency pattern.

In an embodiment, the method 1300 may use a bitmap (e.g., the bitmask1302) that is of a same length as a DL scheduling valid subframeconfiguration along with other parameters such as periodicity. Themethod 1300 may be applied to NPRS transmissions in a guard band (e.g.,guard band 512) or a standalone deployment (e.g., in the frequency band520). The method 1300 may be useful, for example, if it is desirable toschedule NPRSs on invalid DL subframes. In some embodiment, the method1300 may be referred to as a type A configuration or the NPRStime-frequency pattern may be referred to as a type A NPRStime-frequency pattern.

FIG. 14 illustrates an NPRS configuration method 1400 according toembodiments of the present disclosure. The method 1400 may be employedby the BSs 104 and 400 and the UEs 102 and 300. In FIG. 14, the x-axisrepresents time in some constant units and the y-axis representsfrequency in some constant units. In the method 1400, a BS may configurea plurality of positioning subframes 1310 in a plurality of subframes910 within a radio frame 1110 similar to the method 1300. However, theBS may indicate the positioning subframes 1310 by indicating a startingsubframe 1410 (e.g., indexed 1), a number 1412 of positioning subframes1310 starting at the starting subframe 1410, and a periodicity 1414 ofthe positioning subframes 1310. In addition, the BS may schedule DL datain the positioning subframes 1310 and transmit other fixed-scheduledchannel signals in the positioning subframes 1310. To avoid collisions,the BS may determine a time-frequency pattern or time-frequencyresources 1350 for the NPRSs 1340 by puncturing or excludingtime-frequency resources 1370 (e.g., the time-frequency resources 1350)on symbols 212 (e.g., indexed 5, 6, 12, and 13) that are pre-configuredfor fixed-scheduled channel signals irrespective of whether there is anoverlapped time-frequency resource 1350 between the NPRS 1340 and thefixed-scheduled channel signals as shown by the dashed-boxes 1420. Thepunctured NPRS time-frequency resources 1370 are shown as empty-filledboxes. In some embodiments, the fixed-scheduled channel signals arepre-configured for symbols 212 indexed 5 and 6 as shown. Comparing themethods 1300 and 1400, the method 1400 punctures the time-frequencyresources 1370 that can potentially carry an NPRS 1340 in the type A PRSpattern.

In an embodiment, the punctured time-frequency pattern for the NPRSs1340 may be pre-determined and known to BSs and UEs. For example, a BSmay transmit a bitmask 1302 (e.g., a configuration) to indicate thepositioning subframes 1310 in the subframes 910 and transmits the NPRSs1340 in the pre-determined punctured time-frequency pattern. A UE mayreceive the bitmask 1302 and monitor for an NPRS 1340 in the positioningsubframes 1310 indicated by the bitmask 1302. The UE may receive theNPRSs 1340 based on the pre-determined punctured NPRS time-frequencypattern.

In an embodiment, the method 1400 may use a start subframe (e.g., thestarting subframe 1410), a number of subframes (e.g., the number 1412 ofpositioning subframes 1310), and a periodicity (e.g., the periodicity1414). The method 1400 may be useful, for example, when it is desirableto configure NPRSs 1340 on a contiguous set of usable PRBs. In someembodiment, the method 1400 may be referred to as a type B configurationor the NPRS time-frequency pattern may be referred to as a type B PRStime-frequency pattern.

In a network (e.g., the network 100), a BS (e.g., the BSs 104 and 400)may indicate positioning subframes (e.g., the positioning subframes1310) using the methods 1300 and/or 1400. When the BS indicates thepositioning subframes using the type A configuration or both the type Aand the type B configurations, the BS may transmit NPRSs (e.g., theNPRSs 1340) in a pre-determined NPRS time-frequency pattern withoutpuncturing. A UE receiving the type A configuration may receive NPRSsbased on the pre-determined NPRS time-frequency pattern.

Alternatively, when the BS indicates the positioning subframes usingonly the type B configuration, the BS may transmit NPRSs (e.g., theNPRSs 1340) in a pre-determined punctured NPRS time-frequency pattern. AUE receiving the type B configuration may receive NPRSs based on thepre-determined punctured NPRS time-frequency pattern.

In some embodiments, frequency hopping may be optionally configured forthe type B pattern using one or more parameters including a hop durationin number of subframes (e.g., the subframes 910) after which the patternhops, number of hops, list of frequencies/PRBs where the hopping occurs,and a hopping offset. A UE (e.g., the UEs 102 and 300) may compute anext frequency as (e.g., current PRB+hop offset) modulo number ofavailable/allowed PRBs.

In some embodiments, when only type B approach (e.g., the method 1400)is used to configure the PRS (e.g., the NPRSs 1340), the UE may assumethat other NB-IOT signals (e.g., NPSS, NSSS, NPBCH, NB-IOT SIBs, and thelike) are present and, hence, the UE may skip those subframes whileconsidering/processing the configured PRS subframes. When type A (e.g.,the method 1300) or Type A with Type B is used to configure the PRS, theUE may assume that all configured PRS subframes (e.g., the positioningsubframes 1310) are valid PRS subframes. Such a design may be feasible,for example, when using the bitmap (e.g., the bitmask 1302) on a PRBcontaining these signals, as the eNB can always set the bitmap in amanner that skips these subframes. At the same time, having thisflexibility of UE not skipping those subframes enables the eNB to useother PRBs that may not have such signals (e.g., NPSSS, NSSS, and thelike) more efficiently.

In some embodiments, there may also be a dependence on the length of thetype A bitmap. For example, if using a 10 bit bitmap, certain NSSSsubframes may need to be skipped, as NSSS periodicity is typically 20 msand the bitmap cannot be set so that subframe to 0 always. When using 40bit bitmap this is not needed as eNB can configure the bitmap to avoidcollisions with NSSS. Alternately, explicit signaling (e.g., via a bit)may be added which indicates whether the UE should skip these subframesor not.

In some embodiments, the decision to skip one or more of the NPSS, NSSS,NPBCH, NB-IOT SIBs subframes may be based on one or more of thefollowing: the type of configuration used for configuring the PRS (e.g.,type A only, type B only, or type A and type B simultaneously), thelength of the bitmap used for type A configuration, or an explicitlyconfigured bit. For example, when employing type A and B simultaneously,an NPRS may be transmitted in a subframe that is indicated as apositioning subframe by both type A and B configurations.

In some embodiments, when using a type A bitmap to configure PRS on aPRB containing NSSS, NPSSS, NPBCH, SIB, or the like, attention may begiven to ensure that subframes containing these signals are set to 0(i.e. not contain PRS) in the bitmap.

In some embodiments, to benefit from transmit diversity (TxD), a UE mayassume that all PRS signals in one PRS beam occasion use the same beam(but across different PRS beam occasions the beams could be different).For type A configuration, a PRS beam occasion may correspond to a fixedmultiple of the length of the bitmap. For Type B configuration, a PRSbeam occasion may be a fixed multiple of the “num subframe” parameter.In some cases, this fixed multiple may be 1. In an embodiment, a PRSoccasion may be defined in units of subframes (e.g., the subframes 910)and may include N number of subframes corresponding to an N-bit bitmap(e.g., the bitmask 1302).

As described above, a UE 102 may compute timing measurements based onmultiple NPRS received from multiple neighboring BSs 104. One approachto increasing reuse factor for NPRS transmissions is to include blanksubframes (e.g., with no NPRS transmissions) to enable other BSs totransmit NPRSs in the blank subframes. Another approach is to employorthogonal codes. FIG. 15 illustrates a FDMA method 1500 for NPRStransmissions across multiple cells according to embodiments of thepresent disclosure. The method 1500 may be employed by the BSs 104. InFIG. 15, the x-axis represents time in some constant units and they-axis represents frequency in some constant units. In the method 1500,a BS (e.g., the BS 104 a) from one cell (e.g., the coverage area 110 b),denoted as cell 0, may transmit NPRSs (e.g., the NPRSs 220, 532, 730,940) with an orthogonal code, denoted as a, in frequency tones 1520(e.g., the frequency tones 218) across a subframe 1510 and another BS(e.g., the BS 104 b) from another cell (e.g., the coverage area 110 b),denoted as cell 1, may transmit NPRSs with an orthogonal code, denotedas b, in frequency tones 1530 (e.g., the frequency tones 218) across thesubframe 1510 (e.g., the subframes 210, 712, 910, and 1120). The method1500 may enable NPRS transmission from up to 6 cells over 12 frequencysubcarriers or tones.

FIG. 16 illustrates a CDMA-based FDMA method 1600 for NPRS transmissionacross multiple cells according to embodiments of the presentdisclosure. The method 1600 may be employed by the BSs 104. In FIG. 16,the x-axis represents time in some constant units and the y-axisrepresents frequency in some constant units. In the method 1600, two BSs(e.g., the BS 104 a and 104 b) may transmit NPRSs on the same frequencytones 1620 (e.g., the frequency tones 218) across a subframe 1610 (e.g.,the subframes 210, 712, 910, and 1120). For example, a first BS from onecell, denoted as cell 0, may employ an orthogonal code, denoted as a,for NPRS transmission and a second BS from another cell, denoted as cell1, may employ an orthogonal code, denoted as b, for NPRS transmissionwith alternating signs across symbols 1612. Thus, a UE may add orsubtract signals from adjacent symbols 1612 to recover NPRSs from thefirst BS or the second BS, respectively. Thus, the method 1600 maysupport more than six cells for NPRS transmissions. In some embodiments,the orthogonal code length can be chosen to be less than one subframedepending on the assumptions of Doppler. For example, 2 by 6 cells canbe supported with a [+1, −1] code. In some embodiments, the method 1600may be configured with different number of frequency tones and differentorthogonal code lengths to achieve similar functionalities, for example,with 4 frequency tones and an orthogonal code length of 8.

FIG. 17 illustrates an NPRS transmission method 1700 including transmitdiversity according to embodiments of the present disclosure. The method1700 may be employed by the BSs 104. In FIG. 17, the x-axis representstime in some constant units and the y-axis represents frequency in someconstant units. In the method 1700, a BS may transmit NPRSs 1732 and1734 in different beams in different subframes 1710. As shown, the NPRSs1732 are transmitted in a first beam in consecutive subframes 1710 a and1710 b and the NPRSs 1734 are transmitted in a second beam inconsecutive subframes 1710 c and 1710 d. For example, the NPRSs 1732 and1734 have different frequency patterns. As shown, the NPRSs 1732 aretransmitted in frequency tones 1724 and 1728 (e.g., the frequency tones218) in the subframe 1710 a and in frequency tones 1722 and 1726 in thesubframe 1710 b. The NPRSs 1734 are transmitted in frequency tones 1722and 1726 in the subframe 1710 c and in frequency tones 1724 and 1728 inthe subframe 1710 d. When the BS operates with UEs (e.g., UEs 102) thatare unaware of the beam configuration for the NPRS transmission, the BSmay transmit NPRSs in the same beam in a group of subframes 1710. Insome embodiments, the BS may transmit an NPRS configuration includingbeam directions. In such embodiments, the BS may transmit NPRSs usingdifferent beam patterns (e.g., via a pre-determined codebook) acrossrepetitions in a group of subframes 1710. As an example, to scheduleNPRS transmissions for 8 subframes with 4 repetitions and two beamdirections, the BS may use a codebook with (1,1), (1,j), (1, −j), and(1, −1) for the 4 repetitions instead of with (1,1) and a receiving UEmay perform processing based on the codebook.

In some embodiments, one or more of the methods 500 to 1700 describedabove with respect to FIGS. 5 to 17, respectively, may be used inconjunction with each other in any suitable combinations.

FIG. 18 is a flow diagram of a method 1800 of configuring NPRStransmissions according to embodiments of the present disclosure. Stepsof the method 1800 can be executed by a computing device (e.g., aprocessor, processing circuit, and/or other suitable component) of awireless communication device, such as the BSs 104 and 400. The method1800 may employ similar mechanisms as in the methods 500 to 1700. Themethod 1800 can be better understood with reference to FIG. 1. Asillustrated, the method 1800 includes a number of enumerated steps, butembodiments of the method 1800 may include additional steps before,after, and in between the enumerated steps. In some embodiments, one ormore of the enumerated steps may be omitted or performed in a differentorder.

At step 1810, the method 1800 includes determining a configuration for aplurality of positioning subframes (e.g., the positioning subframes 1122and 1310) in a plurality of DL subframes (e.g., the subframes 210, 712,910, 1120, and 1710). The plurality of DL subframes include apre-configured subframes for carrying a pre-determined signals, where ata first positioning subframe of the plurality of positioning subframesoverlaps (e.g., in time and frequency) with the pre-configured subframe.The pre-determined signals may include a NPBCH signal (e.g., the NPBCHsignal 722), a NPSS (e.g., the NPSS 726), a SIB-NB signal (e.g., theSIB-NB signal 724), a NSSS (e.g., the NSSS 728), a LTE CRS (e.g., theCRS 230), a LTE CSI-RS, and/or a NRS.

At step 1820, the method 1800 includes transmitting a plurality of NPRSs(e.g., the NPRSs 220, 531-533, 631, 730, 940, 1130, 1340, 1732, and1734) in the plurality of positioning subframes, for example, to a UEsuch as the UEs 102 and 300. The positioning subframes and thetransmission of the NPRSs may be configured by employing similarmechanisms as described in the methods 500-1700.

In an embodiment, the wireless communication device may configure theconfiguration (e.g., the bitmasks 1140 and 1302) to indicate that theplurality of positioning subframes is invalid for carrying DL data. Thewireless communication device may determine first resources in theplurality of positioning subframes for the plurality of PRSsirrespective of a second resource (e.g., the pre-configured resources1370) in the pre-configured subframe pre-configured for thepre-determined signal, for example, using the method 1300. For example,the first resources may include the second resource. The wirelesscommunication device may transmit the plurality of PRSs using the firstresources and refrain from transmitting the pre-determined signal in thesecond resource.

In an embodiment, the wireless communication device may configure theconfiguration to indicate at least one of a starting subframe (e.g., thestarting subframe 1410) of the DL subframes, a number of the pluralityof positioning subframes(e.g., the number 1412 of positioning subframes1310) beginning at the starting subframe, or a periodicity (e.g., theperiodicity 1414) of the plurality of positioning subframes. Thewireless communication device may determine first resources in theplurality of positioning subframes for the plurality of PRSs byexcluding a second resource (e.g., the pre-configured resources 1370) inthe pre-configured subframe pre-configured for the pre-determined signaland transmit the plurality of PRSs using the first resources.

In an embodiment, the wireless communication device may transmit theconfiguration, for example, to UEs such as the UEs 102 and 300. In anembodiment, the wireless communication device may transmit a firstconfiguration indicating that the plurality of positioning subframes areinvalid for carrying DL data. The wireless communication device mayadditionally transmit a second configuration indicating at least one ofa starting subframe of the DL subframes, a number of second positioningsubframes beginning at the starting subframe, or a periodicity of thesecond positioning subframes. The one of the plurality of positioningsubframes and one of the second positioning subframes correspond to afirst DL subframe of the plurality of DL subframes. The wirelesscommunication device may transmit the plurality of PRSs by transmittinga first PRS of the plurality of PRSs in the first DL subframe.

In an embodiment, the wireless communication device may transmit thePRSs using various frequency bands, such as the an in-band communicationfrequency band (e.g., the frequency band 514) associated with theplurality of DL subframes, a frequency band (e.g., the frequency bands512 and 520) outside of the in-band communication frequency band, or anon-anchoring signal carrier (e.g., the signal carrier 620) of a carrieraggregation associated with the plurality of DL subframes.

In an embodiment, the wireless communication device may transmit a firstPRS of the plurality of PRSs using a first beam and a second PRS of theplurality of PRSs using a different second beam. In some embodiments,the wireless communication device may transmit PRSs in one beamdirection during a set of consecutive subframes (e.g., the positioningsubframes 1310) and switches to another beam direction to transmit PRSsin another set of consecutive subframes.

FIG. 19 is a flow diagram of a method 1900 of processing NPRSs accordingto embodiments of the present disclosure. Steps of the method 1900 canbe executed by a computing device (e.g., a processor, processingcircuit, and/or other suitable component) of a wireless communicationdevice, such as the UEs 102 and 300. The method 1900 may employ similarmechanisms as in the methods 500 to 1700. The method 1900 can be betterunderstood with reference to FIG. 1. As illustrated, the method 1900includes a number of enumerated steps, but embodiments of the method1900 may include additional steps before, after, and in between theenumerated steps. In some embodiments, one or more of the enumeratedsteps may be omitted or performed in a different order.

At step 1910, the method 1900 includes receiving a plurality of NPRSs(e.g., the NPRSs 220, 531-533, 631, 730, 940, 1130, 1340, 1732, and1734) in a plurality of positioning subframes (e.g., the positioningsubframes 1122 and 1310) of a plurality of DL subframes (e.g., thesubframes 210, 712, 910, 1120, and 1510), for example, from a BS such asthe BSs 104 and 400. The plurality of DL subframes include apre-configured subframe for carrying a pre-determined signals, wherein afirst positioning subframe of the plurality of positioning subframesoverlaps (e.g., in time and frequency) with the pre-configuredsubframes. The pre-determined signals may include a NPBCH signal (e.g.,the NPBCH signal 722), a NPSS (e.g., the NPSS 726), a SIB-NB signal(e.g., the SIB-NB signal 724), a NSSS (e.g., the NSSS 728), a LTE CRS(e.g., the CRS 230), a LTE CSI-RS, and/or a NRS.

At step 1920, the method 1900 includes computing a timing measurement(e.g., TOA) based on the plurality of NPRSs.

In an embodiment, the wireless communication device receives aconfiguration indicating the plurality of positioning subframes in theplurality of DL subframes, wherein the receiving is based on theconfiguration.

In an embodiment, the configuration may indicate that the plurality ofpositioning subframes is invalid for carrying DL data. The configurationmay include a bitmap (e.g., the bitmasks 1140 and 1302) including aplurality of bits associated with the plurality of DL subframes, each ofthe plurality of bits indicating whether a corresponding DL subframe isinvalid for carrying the DL data. The wireless communication device mayreceive th plurality of PRSs from first resources during the pluralityof positioning subframes, the first resources including a secondresource (e.g., the pre-configured time-frequency resources 1370) in thepre-configured subframe pre-configured for the pre-determined signal.

In an embodiment, the configuration may indicate at least one of astarting subframe (e.g., the starting subframe 1410) of the DLsubframes, a number of the plurality of positioning subframes (e.g., thenumber 1412 of positioning subframes) beginning at the startingsubframe, or a periodicity (e.g., the periodicity 1414) of the pluralityof positioning subframes. The wireless communication device may receivethe plurality of PRSs from first resources during the plurality ofpositioning subframes, the first resources excluding a second resourcein the pre-configured subframe pre-configured for the pre-determinedsignal.

In an embodiment, the wireless communication device may receive a firstconfiguration from a BS indicating that the plurality of positioningsubframes are invalid for carrying DL data. The wireless communicationdevice may additionally receive a second configuration indicating atleast one of a starting subframe of the DL subframes, a number of secondpositioning subframes beginning at the starting subframe, or aperiodicity of the second positioning subframes, wherein one of theplurality of positioning subframes and one of the second positioningsubframes correspond to a first DL subframe of the plurality of DLsubframes. The wireless communication device may receive the pluralityof PRSs by receiving a first PRS of the plurality of PRSs in the firstDL subframe.

In an embodiment, the wireless communication device may receive the PRSsfrom various frequency bands, such as the an in-band communicationfrequency band (e.g., the frequency band 514) associated with theplurality of DL subframes, a frequency band (e.g., the frequency bands512 and 520) outside of the in-band communication frequency band, or anon-anchoring signal carrier (e.g., the signal carrier 620) of a carrieraggregation associated with the plurality of DL subframes.

In an embodiment, the wireless communication device may receive a firstPRS of the plurality of PRSs from a first beam and a second PRS of theplurality of PRSs from a different second beam. In some embodiments, thewireless communication device may receive PRSs from one beam directionduring a set of consecutive subframes (e.g., the positioning subframes1310) and switches to another beam direction to receive PRSs fromanother set of consecutive subframes.

FIG. 20 is a flow diagram of a method 2000 of communicating NPRSsaccording to embodiments of the present disclosure. Steps of the method2000 can be executed by a computing device (e.g., a processor,processing circuit, and/or other suitable component) of a wirelesscommunication device, such as the UEs 102 and 300. The method 2000 mayemploy similar mechanisms as in the methods 500 to 1900. The method 2000can be better understood with reference to FIG. 1. As illustrated, themethod 2000 includes a number of enumerated steps, but embodiments ofthe method 2000 may include additional steps before, after, and inbetween the enumerated steps. In some embodiments, one or more of theenumerated steps may be omitted or performed in a different order.

At step 2010, the method includes determining, by a first wirelesscommunication device, a time-frequency PRS pattern based at least inpart on a narrowband communication frequency band configuration (e.g.,the frequency bands 512, 514, 520, and 620) and a PRS subframeconfiguration mode (e.g., type A or type B) associated with a set ofsubframes (e.g., the positioning subframes 1122 and 1310).

Each subframe of the set of subframes includes a plurality of frequencytones (e.g., the frequency tones 218) in a plurality of symbols (e.g.,the symbols 212), and wherein the time-frequency PRS pattern includestime-frequency resources (e.g., the time-frequency resource 1350) in asubset of the plurality of frequency tones in a subset of the pluralityof symbols. The time-frequency PRS pattern can include at least onetime-frequency resource in each symbol of the plurality of symbols.

At step 2020, the method includes communicating, by the first wirelesscommunication device with a second wireless communication device, aplurality of PRSs (e.g., the NPRSs 220, 531-533, 631, 730, 940, 1130,1340, 1732, and 1734) using the determined PRS time-frequency pattern inthe set of subframes. In an embodiment, the first wireless communicationdevice may be a BS and the second wireless communication device may be aUE. In an embodiment, the first wireless communication device may be aUE and the second wireless communication device may be a BS.

In an embodiment, the first wireless communication device can furtherdetermine that the narrowband communication frequency band configurationindicates at least one of a guard band (e.g., the frequency bands 512)of a wideband communication frequency band (e.g., the frequency bands510), an in-band frequency band (e.g., the frequency bands 514) withinthe wideband communication frequency band, or a standalone frequencyband (e.g., the frequency bands 520) independent of the widebandcommunication frequency band. In an embodiment, the widebandcommunication frequency band is a non-anchoring carrier frequency band(e.g., the non-anchoring signal carrier 620) of a widebandcommunication.

In an embodiment, the first wireless communication device can determinetime-frequency PRS pattern by determining a first time-frequency PRSpattern when the narrowband communication frequency band configurationincludes the guard band or the standalone frequency band and determininga second time-frequency PRS pattern different than the firsttime-frequency PRS pattern when the narrowband communication frequencyband configuration includes the in-band frequency band.

In an embodiment, the first wireless communication device can determinethat a PRS configuration of the PRS subframe configuration modeindicates at least one of a first configuration (e.g., type A) or asecond configuration (e.g., type B) based on the narrowbandcommunication frequency band configuration. The first configurationincluding a bitmap (e.g., the bitmask 1302) indicating a set of PRSsubframes (e.g., the positioning subframes 1310) positioned within agroup of contiguous subframes (e.g., the subframes 910) the bitmapincluding a length corresponding to a number of subframes in the groupof contiguous subframes. The second configuration indicating a subset ofthe group of contiguous subframes by including at least one of astarting subframe (e.g., the starting subframe 1410) for the subset, anumber of subframes (e.g., the number 1412 of positioning subframes) inthe subset, or a periodicity (e.g., the periodicity 1414) of the subset.The first wireless communication device can communicate the PRSconfiguration with the second wireless communication device.

In an embodiment, the first wireless communication device can determinethat the time-frequency PRS pattern includes a predeterminedtime-frequency PRS pattern without puncturing any time-frequencyresource from the predetermined time-frequency PRS pattern based on apredetermined narrowband communication reference signal when the PRSsubframe configuration mode indicates the first configuration or acombination of the first configuration and the second configuration, forexample, as shown in the method 1300 described with respect to FIG. 13.

In an embodiment, the first wireless communication device can determinethat the time-frequency PRS pattern includes a predeterminedtime-frequency PRS pattern with at least one time-frequency resourcepunctured (e.g., the NPRS punctured time-frequency resources 1370) fromthe predetermined time-frequency PRS pattern based on a predeterminednarrowband communication reference signal (e.g., an NRS) when the PRSsubframe configuration mode indicates the second configuration withoutthe first configuration, for example, as shown in the method 1400described with respect to FIG. 14. In some instances, when the firstwireless communication device is a UE, the first wireless communicationdevice may skip any symbol within a subframe that is pre-configured fora predetermined narrowband communication reference signal.

In an embodiment, the first wireless communication device cancommunicate the plurality of PRSs in the subset of the group ofcontiguous subframes by excluding a PRS transmission in the subset thatare preconfigured for a predetermined narrowband communication broadcastsignal when the PRS subframe configuration mode indicates the secondconfiguration without the first configuration. The predeterminednarrowband communication broadcast signal includes at least one of aNPSS, a NSSS, a NPBCH signal, or a narrowband system information blockpart-one (NSIB1) signal.

In an embodiment, the first wireless communication device cancommunicate the plurality of PRSs in subframes that are within thesubset of the group of contiguous subframes indicated by the secondconfiguration and within the set of PRS subframes indicated by the firstconfiguration when the PRS subframe configuration mode indicates thecombination of the first configuration and the second configuration.

In an embodiment, the first wireless communication device cancommunicate the plurality of PRSs in the in-band frequency band byexcluding a PRS transmission in one or more symbols within the set ofsubframes that are associated with a wideband communication in thewideband communication frequency band. The one or more symbols withinthe set of subframes includes at least one of a transmission of acell-specific reference signal (CRS) of the wideband communication or atransmission of a physical downlink control channel (PDCCH) signal ofthe wideband communication. In an embodiment, the wideband communicationmay be a LTE communication. The one or more symbols can include symbolsindexed 0, 4, 7, and 11 of a subframe when the LTE communication usesone or two CRS ports (e.g., antenna ports). The one or more symbols caninclude symbols indexed 1 and 8 of a subframe when the LTE communicationuses four CRS ports. The one or more symbols can include symbols indexed0, 1, and 2 of a subframe reserved for PDCCH transmissions.

In an embodiment, the first wireless communication device cancommunicate information associated with the wideband communication(e.g., a LTE communication) including at least one of a subframeconfiguration indicating the one or more symbols or a PRS configurationof the wideband communication. The information may be referred to asassistance information. The assistance information can include asubframe offset with respect to a serving cell of the first and secondwireless communication devices, a radio frame offset with respect to theserving cell, a number of CRS ports, a number of NRS ports, a validsubframe bitmap configuration. For in-band deployment, the assistanceinformation can include other configured PRS such as LTE PRSs sent on awider bandwidth, a bandwidth of LTE cell, a number of LTE controlsymbols, and symbol locations for CSI-RSs for one or more of serving andneighboring cells.

In an embodiment, the first wireless communication device cancommunicate the plurality of PRSs by communicating a first subset of theplurality of PRSs (e.g., the NPRSs 1732) using a first beam during afirst time period corresponding to the bitmap or the periodicity andcommunicating a second subset of the plurality of PRSs (e.g., the NPRSs1734) using a second beam during a repeating time period correspondingto the bitmap or the periodicity, the first beam and the second beaminclude different beam directions.

In an embodiment, the first wireless communication device cancommunicate the plurality of PRSs by communicating a first PRS (e.g.,the NPRSs 1732) of the plurality of PRSs using a first beam andcommunicating a second PRS (e.g., the NPRSs 1734) of the plurality ofPRSs using a second beam, the first beam and the second beam includedifferent beam directions.

In some embodiments, a network (e.g., the network 100) may employ a newpositioning reference signal for OTDOA in NB-IoT that is not based onexisting LTE Release 13 NB-IoT signal and not based on LTE CRS. Thesubframes (e.g., the positioning subframes 1310) which contain NPRS(e.g., the NPRSs 1340) are configured by higher-layers. Per NB-IoTcarrier, it may configure the subframes used for NPRS transmission suchthat NPRS do not occur in subframes containing transmissions to LTERelease 13 UEs in the cell of NPDCCH, NPDSCH, NPBCH, and NPSS/NSSS.

In an embodiment of configuration of time resources for NPRS, indicationof exact subframes is by part A or type A (e.g., the method 1300): Abitmap (e.g., the bitmask 1302) on subframes which are not NB-IoT DLsubframes (i.e. invalid DL subframes). In an embodiment of type A, thebitmap is a fixed length of 10 bits. In an embodiment of type A, thebitmap is the same length as valid subframe configuration, i.e. 10 bitsor 40 bits. In an embodiment of type A, the bitmap is a fixed length ofx bits (e.g., x=20).

In an embodiment of part B or type B (e.g., the method 1400), indicatedwith one start subframe (e.g., the starting subframe 1410), oneperiodicity (e.g., the periodicity 1414), and one number of repetitions(e.g., the number 1412 of subframes) for the occasions. On an anchorcarrier (e.g., the carrier 610), type A and/or type B may be used. On anon-anchor carrier (e.g., the carrier 620), type A and/or type B may beused. Indication of NPRS muting patterns is indicated with a periodicNPRS muting sequence.

In an embodiment of an in-band scenario (e.g., the frequency band 514),the NPRS subframe configuration is type A or (type A and type B). Thelegacy LTE PRS pattern in on PRB is adopted. In an embodiment of astandalone (e.g., the frequency band 520) or guard-band scenario (e.g.,the frequency bands 512), the NPRS subframe configuration is type A or(type A and type B). If NPRS subframe configuration is type B, NPRS ispunctured in OFDM symbols 5 and 6 in each slot (e.g., as shown in themethod 1400).

In an embodiment, the slotNumberOffset and SFN_offset between areference cell and a neighbor cell for OTDOA in NB-IoT can optionally beincluded in assistance data for OTDOA. The slotNumberOffset correspondsto the number of full slots counted from the beginning of a radio frameof the assistance data reference cell to the beginning of the closestsubsequent radio frame of the neighbor cell. The SFN_offset correspondsto the number of full radio frames counted from the beginning of a radioframe #0 of the assistance data reference cell to the beginning of theclosest subsequent radio frame #0 of the neighbor cell.

In an embodiment, per Per NB-IoT carrier configured for NPRS, a UE mayassume the same precoder is used for a number of NPRS subframescorresponding to the length of a bitmap for type A or (type A and typeB) and a “number of subframe” parameter for type B only.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of [at least one of A, B, or C]means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

Embodiments of the present disclosure include a method of wirelesscommunication, comprising configuring, by a wireless communicationdevice, a plurality of positioning subframes of a plurality of downlink(DL) subframes, wherein the plurality of DL subframes include one ormore pre-configured subframes for carrying one or more pre-determinedsignals, and wherein at least one of the plurality of positioningsubframes are non-overlapping with the one or more pre-configuredsubframes; and transmitting, by the wireless communication device, aplurality of narrowband positioning reference signals (NPRSs) in theplurality of positioning subframes.

The method further includes wherein the plurality of NPRSs is associatedwith Q repetitions of a frequency pattern, wherein Q is a positiveinteger, and wherein the configuring the plurality of positioningsubframes includes identifying N consecutive subframes in the pluralityof DL subframes that are non-overlapping with the one or morepre-configured subframes, wherein N is a positive integer; andconfiguring the plurality of positioning subframes in Q consecutivesubframes of the N consecutive subframes when Q is less than or equal toN. The method further includes wherein the configuring the plurality ofpositioning subframes further includes configuring the plurality ofpositioning subframes in the N consecutive subframes when Q is greaterthan N, and wherein the transmitting the plurality of NPRSs when Q isgreater than N includes transmitting the plurality of NPRSs associatedwith N of the Q repetitions in the N consecutive subframes; and dropping(Q-N) of the Q repetitions for transmission. The method further includeswherein the configuring the plurality of positioning subframes furtherincludes configuring the plurality of positioning subframes in the Nconsecutive subframes and at least one following subframe that isnon-overlapping with the one or more pre-configured subframes when Q isgreater than N, and wherein the N consecutive subframes and the at leastone following subframe are separated by at least one of the one or morepre-configured subframes. The method further includes wherein thepre-determined signals include at least one of a narrowband broadcastchannel (NBCH) signal, a system information block-narrowband (SIB-NB)signal, a narrowband primary synchronization (NPSS), a narrowbandsecondary synchronization signal (NSSS), a narrowband reference signal(NRS), a Long-Term Evolution (LTE) cell-specific reference signal (CRS),a LTE channel state information-reference signal (CSI-RS), or a LTEpositioning reference signal (PRS). The method further includes whereina first positioning subframe of the plurality of positioning subframesoverlaps with a first pre-configured subframe of the one or morepre-configured subframes, wherein the first pre-configured subframeincludes a first frequency tone pre-configured for one of the one ormore pre-determined signals, and wherein the transmitting the pluralityof NPRSs includes transmitting a first NPRS of the plurality of NPRSs inthe first positioning subframe on a second frequency tone different thanthe first frequency tone. The method further includes wherein a firstpositioning subframe of the plurality of positioning subframes overlapswith a first pre-configured subframe of the one or more pre-configuredsubframes, wherein the first pre-configured subframe includes a firstfrequency tone pre-configured for a first pre-determined signal of theone or more pre-determined signals, and wherein the transmitting theplurality of NPRSs includes transmitting a first NPRS of the pluralityof NPRSs in the first positioning subframe by transmitting the firstNPRS in the first frequency tone; and excluding transmission of thefirst pre-determined signal in the first frequency tone. The methodfurther includes transmitting, by the wireless communication device to auser equipment (UE), a DL schedule indicating that the plurality ofpositioning subframes are invalid DL subframes for carrying DL data. Themethod further includes transmitting, by the wireless communicationdevice to a user equipment (UE), a DL schedule indicating that at leastone of the plurality of positioning subframes is a valid DL subframe forcarrying DL data. The method further includes wherein the plurality ofDL subframes are associated with an anchoring signal carrier of acarrier aggregation, and wherein the plurality of positioning subframesare associated with a non-anchoring signal carrier of the carrieraggregation. The method further includes wherein the plurality ofpositioning subframes include a first subset of consecutive subframesand a second subset of consecutive subframes of the plurality of DLsubframes, and wherein the transmitting the plurality of NPRSs includestransmitting first NPRSs of the plurality of NPRSs associated with afirst frequency pattern in the first subset of consecutive subframes;and transmitting second NPRSs of the plurality of NPRSs associated witha second frequency pattern in the second subset of consecutivesubframes, wherein the first frequency pattern and the second frequencypattern are different. The method further includes wherein the pluralityof positioning subframes includes a first subset of consecutivesubframes and a second subset of consecutive subframes of the pluralityof DL subframes, and wherein the transmitting the plurality of NPRSsincludes transmitting first NPRSs of the plurality of NPRSs on a firstbeam in the first subset of consecutive subframes; and transmittingsecond NPRSs of the plurality of NPRSs on a second beam in the secondsubset of consecutive subframes, wherein the first beam and the secondbeam are different. The method further includes wherein the transmittingthe plurality of NPRSs includes applying orthogonal codes to theplurality of NPRSs. The method further includes wherein the plurality ofNPRSs are transmitted in frequency tones that are shared among differentcells for NPRS transmission.

Embodiments of the present disclosure further include a method ofwireless communication, comprising receiving, by a wirelesscommunication device, a plurality of narrowband positioning referencesignal (NPRSs) in a plurality of positioning subframes of a plurality ofdownlink (DL) subframes, wherein the plurality of DL subframes includeone or more pre-configured subframes for carrying one or morepre-determined signals, and wherein at least one of the plurality ofpositioning subframes are non-overlapping with the one or morepre-configured subframes; and computing, by the wireless communicationdevice, a timing measurement based on the plurality of NPRSs.

The method further includes receiving, by the wireless communicationdevice, NPRS configuration information associated with at least one of asubframe configuration of the plurality of positioning subframes, a beamdirection configuration of the plurality of NPRSs, or a DL schedule inat least one of the plurality of positioning subframes. The methodfurther includes decoding, by the wireless communication device, DL datain a first positioning subframe by excluding at least one of a pluralityof frequency tones in the first positioning subframe that carries one ofthe plurality of NPRSs. The method further includes wherein theplurality of NPRSs are received from a non-anchoring signal carrier thatis different from an anchoring signal carrier associated with the one ormore pre-configured subframes. The method further includes wherein theplurality of NPRSs is encoded with an orthogonal code, and wherein thetiming measurement is computed based on the orthogonal code.

Embodiments of the present disclosure include an apparatus comprisingmeans for determining a time-frequency positioning reference signal(PRS) pattern based at least in part on a narrowband communicationfrequency band configuration and a PRS subframe configuration modeassociated with a set of subframes; and means for communicating, with asecond wireless communication device, a plurality of PRSs using thedetermined PRS time-frequency pattern in the set of subframes.

The apparatus further includes wherein each subframe of the set ofsubframes includes a plurality of frequency tones in a plurality ofsymbols, and wherein the time-frequency PRS pattern includestime-frequency resources in a subset of the plurality of frequency tonesin a subset of the plurality of symbols. The apparatus further includeswherein the means for determining the time-frequency PRS pattern isfurther configured to determine the time-frequency PRS pattern based ona predetermined time-frequency PRS pattern including at least onetime-frequency resource in each symbol of the plurality of symbols. Theapparatus further includes means for determining that the narrowbandcommunication frequency band configuration indicates at least one of aguard band of a wideband communication frequency band, an in-bandfrequency band within the wideband communication frequency band, or astandalone frequency band independent of the wideband communicationfrequency band. The apparatus further includes wherein the widebandcommunication frequency band is a non-anchoring carrier frequency bandof a wideband communication. The apparatus further includes wherein themeans for determining the time-frequency PRS pattern is furtherconfigured to determine a first time-frequency PRS pattern when thenarrowband communication frequency band configuration includes the guardband or the standalone frequency band; and determine a secondtime-frequency PRS pattern different than the first time-frequency PRSpattern when the narrowband communication frequency band configurationincludes the in-band frequency band. The apparatus further includesmeans for determining that a PRS configuration of the PRS subframeconfiguration mode indicates at least one of a first configuration or asecond configuration based on the narrowband communication frequencyband configuration, the first configuration including a bitmapindicating a set of PRS subframes positioned within a group ofcontiguous subframes, the bitmap including a length corresponding to anumber of subframes in the group of contiguous subframes, and the secondconfiguration indicating a subset of the group of contiguous subframesby including at least one of a starting subframe for the subset, anumber of subframes in the subset, or a periodicity of the subset. Theapparatus further includes means for communicating, with the secondwireless communication device, the PRS configuration. The apparatusfurther includes means for determining the time-frequency PRS pattern isfurther configured to determine that the time-frequency PRS patternincludes a predetermined time-frequency PRS pattern without puncturingany time-frequency resource from the predetermined time-frequency PRSpattern based on a predetermined narrowband communication referencesignal when the PRS subframe configuration mode indicates the firstconfiguration or a combination of the first configuration and the secondconfiguration. The apparatus further includes wherein the means fordetermining the time-frequency PRS pattern is further configured todetermine that the time-frequency PRS pattern includes a predeterminedtime-frequency PRS pattern with at least one time-frequency resourcepunctured from the predetermined time-frequency PRS pattern based on apredetermined narrowband communication reference signal when the PRSsubframe configuration mode indicates the second configuration withoutthe first configuration. The apparatus further includes wherein themeans for communicating the plurality of PRSs is further configured tocommunicate the plurality PRSs by communicating the plurality of PRSs inthe subset of the group of contiguous subframes by excluding a PRStransmission in the subset that are preconfigured for a predeterminednarrowband communication broadcast signal when the PRS subframeconfiguration mode indicates the second configuration without the firstconfiguration. The apparatus further includes wherein the predeterminednarrowband communication broadcast signal includes at least one of anarrowband primary synchronization signal (NPSS), a narrowband secondsynchronization signal (NSSS), a narrowband physical broadcast channel(NPBCH) signal, or a narrowband system information block part-one(NSIB1) signal. The apparatus further includes wherein the means forcommunicating the plurality of PRSs is further configured to communicatethe plurality of PRSs in subframes that are within the subset of thegroup of contiguous subframes indicated by the second configuration andwithin the set of PRS subframes indicated by the first configurationwhen the PRS subframe configuration mode indicates the combination ofthe first configuration and the second configuration. The apparatusfurther includes wherein the means for communicating the plurality ofPRSs is further configured to communicate the plurality of PRSs in thein-band frequency band by excluding a PRS transmission in one or moresymbols within the set of subframes that are associated with a widebandcommunication in the wideband communication frequency band. Theapparatus further includes wherein the one or more symbols within theset of subframes includes at least one of a transmission of acell-specific reference signal (CRS) of the wideband communication or atransmission of a physical downlink control channel (PDCCH) signal ofthe wideband communication. The apparatus further includes means forcommunicating, with second wireless communication device, informationassociated with the wideband communication including at least one of asubframe configuration indicating the one or more symbols or a PRSconfiguration of the wideband communication. The apparatus furtherincludes wherein the means for communicating the plurality of PRSs isfurther configured to communicate a first subset of the plurality ofPRSs using a first beam during a first time period corresponding to thebitmap or the periodicity; and communicate a second subset of theplurality of PRSs using a second beam during a repeating time periodcorresponding to the bitmap or the periodicity, the first beam and thesecond beam include different beam directions. The apparatus furtherincludes wherein the means for communicating the plurality of PRSs isfurther configured to communicate a first PRS of the plurality of PRSsusing a first beam; and communicate a second PRS of the plurality ofPRSs using a second beam, the first beam and the second beam includedifferent beam directions.

As those of some skill in this art will by now appreciate and dependingon the particular application at hand, many modifications, substitutionsand variations can be made in and to the materials, apparatus,configurations and methods of use of the devices of the presentdisclosure without departing from the spirit and scope thereof. In lightof this, the scope of the present disclosure should not be limited tothat of the particular embodiments illustrated and described herein, asthey are merely by way of some examples thereof, but rather, should befully commensurate with that of the claims appended hereafter and theirfunctional equivalents.

What is claimed is:
 1. A method of wireless communication performed by auser equipment (UE), the method comprising: receiving a configurationsignal including: a first indication signal including a narrowbandpositioning reference signal (NPRS) bitmap for a group of subframes, theNPRS bitmap including a length corresponding to a number of subframes inthe group of subframes, wherein the NPRS bitmap indicates a firstsubframe of the group of subframes, the first subframe including a firstNPRS; and receiving, based on the first indication signal, the firstNPRS in the first subframe.
 2. The method of claim 1, wherein thereceiving the first NPRS comprises: receiving the first NPRS in anin-band frequency band.
 3. The method of claim 2, wherein the firstindication signal includes an indication of the in-band frequency band.4. The method of claim 1, wherein the receiving the first NPRScomprises: receiving the first NPRS in a guard band.
 5. The method ofclaim 4, wherein the first indication signal includes an indication ofthe guard band.
 6. The method of claim 1, wherein the receiving thefirst NPRS comprises: receiving the first NPRS in a standalone band. 7.The method of claim 6, wherein the first indication signal includes anindication of the standalone band.
 8. The method of claim 1, wherein thelength of the NPRS bitmap is 10 bits.
 9. The method of claim 1, whereinthe length of the NPRS bitmap is 40 bits.
 10. A user equipment,comprising: a memory; a transceiver; and a processor communicativelycoupled to the memory and the transceiver, wherein the user equipment isconfigured to: receive a configuration signal including: a firstindication signal including a narrowband positioning reference signal(NPRS) bitmap for a group of subframes, the NPRS bitmap including alength corresponding to a number of subframes in the group of subframes,wherein the NPRS bitmap indicates a first subframe of the group ofsubframes, the first subframe including a first NPRS; and receive, basedon the first indication signal, the first NPRS in the first subframe.11. The user equipment of claim 10, wherein the user equipment isconfigured to receive the first NPRS by: receiving the first NPRS in anin-band frequency band.
 12. The user equipment of claim 11, wherein thefirst indication signal includes an indication of the in-band frequencyband.
 13. The user equipment of claim 10, wherein the user equipment isconfigured to receive the first NPRS by: receiving the first NPRS in aguard band.
 14. The user equipment of claim 13, wherein the firstindication signal includes an indication of the guard band.
 15. The userequipment of claim 10, wherein the user equipment is configured toreceive the first NPRS by: receiving the first NPRS in a standaloneband.
 16. The user equipment of claim 15, wherein the first indicationsignal includes an indication of the standalone band.
 17. The userequipment of claim 10, wherein the length of the NPRS bitmap is 10 bits.18. The user equipment of claim 10, wherein the length of the NPRSbitmap is 40 bits.
 19. A user equipment, comprising: means for receivinga configuration signal including: a first indication signal including anarrowband positioning reference signal (NPRS) bitmap for a group ofsubframes, the NPRS bitmap including a length corresponding to a numberof subframes in the group of subframes, wherein the NPRS bitmapindicates a first subframe of the group of subframes, the first subframeincluding a first NPRS; and means for receiving, based on the firstindication signal, the first NPRS in the first subframe.
 20. The userequipment of claim 19, wherein the means for receiving the first NPRScomprises: means for receiving the first NPRS in an in-band frequencyband.
 21. The user equipment of claim 20, wherein the first indicationsignal includes an indication of the in-band frequency band.
 22. Theuser equipment of claim 19, wherein the means for receiving the firstNPRS comprises: means for receiving the first NPRS in a guard band. 23.The user equipment of claim 22, wherein the first indication signalincludes an indication of the guard band.
 24. The user equipment ofclaim 19, wherein the means for receiving the first NPRS comprises:means for receiving the first NPRS in a standalone band.
 25. The userequipment of claim 24, wherein the first indication signal includes anindication of the standalone band.
 26. The user equipment of claim 19,wherein the length of the NPRS bitmap is 10 bits.
 27. The user equipmentof claim 19, wherein the length of the NPRS bitmap is 40 bits.
 28. Anon-transitory computer-readable medium having program code recordedthereon for execution by a user equipment, the program code comprising:code for causing the user equipment to receive a configuration signalincluding: a first indication signal including a narrowband positioningreference signal (NPRS) bitmap for a group of subframes, the NPRS bitmapincluding a length corresponding to a number of subframes in the groupof subframes, wherein the NPRS bitmap indicates a first subframe of thegroup of subframes, the first subframe including a first NPRS; and codefor causing the user equipment to receive, based on the first indicationsignal, the first NPRS in the first subframe.
 29. The non-transitorycomputer-readable medium of claim 28, wherein the code for causing theuser equipment to receive the first NPRS comprises: code for causing theuser equipment to receive the first NPRS in an in-band frequency band.30. The non-transitory computer-readable medium of claim 28, wherein thecode for causing the user equipment to receive the first NPRS comprises:code for causing the user equipment to receive the first NPRS in a guardband.